With the development of science and technology, now large granule or powder, etc., material packaging enterprises (such as, rice, flour, feedstuff, fertilizers, etc.) all utilize automated process line, and the full-automatic weighing and packaging device is sufficiently used. Currently, the material bag supply and the bag mouth opening are completed by gripping and adsorbing via a sucker on the full-automatic weighing and packaging device. The granule or powder packages employ PP bags which are knitted vertically and horizontally by approximately 2 mm of woven strips, with very high breathability. Thus the suckers can not be used to open the bag mouth when using the full-automatic weighing and packaging device, and the woven bags must be treated with double-sided lamination processing to solve the problem of breathability, and the woven membrane reduces production efficiency and increases the cost, therefore the full-automatic weighing and packaging device is not universally used by many of the enterprises.